Isolation of an antimicrobial compound produced by bacteria associated with reef-building corals

Jean-Baptiste Raina; Dianne Tapiolas; Cherie A Motti; Sylvain Foret; Torsten Seemann; Jan Tebben; Bette L Willis; David G Bourne

doi:10.7717/peerj.2275

Isolation of an antimicrobial compound produced by bacteria associated with reef-building corals

PeerJ. 2016 Aug 18:4:e2275. doi: 10.7717/peerj.2275. eCollection 2016.

Authors

Jean-Baptiste Raina¹, Dianne Tapiolas², Cherie A Motti², Sylvain Foret³, Torsten Seemann⁴, Jan Tebben⁵, Bette L Willis⁶, David G Bourne⁷

Affiliations

¹ Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, Australia; Australian Institute of Marine Science, Townsville, QLD, Australia; Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, Australia; Marine Biology and Aquaculture, College of Science and Engineering, James Cook University of North Queensland, Townsville, QLD, Australia; AIMS@JCU, James Cook University, Townsville, QLD, Australia.
² Australian Institute of Marine Science , Townsville, QLD , Australia.
³ Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, Australia; Research School of Biology, Australian National University, Canberra, ACT, Australia.
⁴ Victorian Life Sciences Computation Initiative, University of Melbourne , Melbourne, Victoria , Australia.
⁵ Section Chemical Ecology, Alfred Wegener Institute, Bremerhaven, Germany; University of New South Wales, Sydney, NSW, Australia.
⁶ Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD, Australia; Marine Biology and Aquaculture, College of Science and Engineering, James Cook University of North Queensland, Townsville, QLD, Australia.
⁷ Australian Institute of Marine Science, Townsville, QLD, Australia; Marine Biology and Aquaculture, College of Science and Engineering, James Cook University of North Queensland, Townsville, QLD, Australia.

Abstract

Bacterial communities associated with healthy corals produce antimicrobial compounds that inhibit the colonization and growth of invasive microbes and potential pathogens. To date, however, bacteria-derived antimicrobial molecules have not been identified in reef-building corals. Here, we report the isolation of an antimicrobial compound produced by Pseudovibrio sp. P12, a common and abundant coral-associated bacterium. This strain was capable of metabolizing dimethylsulfoniopropionate (DMSP), a sulfur molecule produced in high concentrations by reef-building corals and playing a role in structuring their bacterial communities. Bioassay-guided fractionation coupled with nuclear magnetic resonance (NMR) and mass spectrometry (MS), identified the antimicrobial as tropodithietic acid (TDA), a sulfur-containing compound likely derived from DMSP catabolism. TDA was produced in large quantities by Pseudovibrio sp., and prevented the growth of two previously identified coral pathogens, Vibrio coralliilyticus and V. owensii, at very low concentrations (0.5 μg/mL) in agar diffusion assays. Genome sequencing of Pseudovibrio sp. P12 identified gene homologs likely involved in the metabolism of DMSP and production of TDA. These results provide additional evidence for the integral role of DMSP in structuring coral-associated bacterial communities and underline the potential of these DMSP-metabolizing microbes to contribute to coral disease prevention.

Keywords: Alphaproteobacteria; Antimicrobial compounds; Coral-associated bacteria; Disease.

Grants and funding

This work was supported by the ARC Centre of Excellence for Coral Reef Studies, AIMS@JCU, James Cook University and the Australian Institute of Marine Science. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.